Hydraulic brakes and spoked wheel support.

4banger

4banger

Member
When installing 46-48 ford hydraulic brakes on a Model A and using the original 21" wheels,you need to install adapter rings to get 2 point support at each lug hole. My question is does the outer rim of the spoked wheel hub need to make contact with the brake drum as it does with the original Model A steel brake drums? It seems as it should to support the spoke area of the outer rim of the wheel hub.
 
While others may differ the on their opinion, it certainly appears to me that the wheel hub to drum fit is calculated and part of the structure.

You will find some of the original Ford drums are even machined on the areas where the wheel touches the drum. I can not help but think there is an important structural relationship. Without the drum support I have to think the spoke to hub area has to be weakened when run without the A drum. I have to believe there is a lot of flexing.

Conversely I would have to think the drums would be more prone to problems when run with none Model A wheels.

More reasons why the original systems are better then trying to change things.

Now saying all the above, many people have been running with these various setups and I have not heard that there are problems. That is not to say there are problems, many just ignore them or never notice them.

In any event, that is my opinion. It may be completely wrong.
 
i would think if the wheel to hub fit was good & the 21' wheels are good there would be no problem . but im running mechanicals & 16" wheels , what do i know ..... LOL
,.. steve
 
4banger said:
When installing 46-48 ford hydraulic brakes on a Model A and using the original 21" wheels,you need to install adapter rings to get 2 point support at each lug hole. My question is does the outer rim of the spoked wheel hub need to make contact with the brake drum as it does with the original Model A steel brake drums? It seems as it should to support the spoke area of the outer rim of the wheel hub.
Click to expand...

Daves right, if you only have support on the lug nuts, thats prone to alot of bad leverage, especially, side ways. I dont think I have ever seen a wheel on anything that didn't have support, unless like mags, that were designed that way. Just isn't worth taking a chance with you, or your families life. Herm.
 
The adapter plates for wire wheels onto 40's brake drums have a long track record and support the wheel just fine. If you do not use adapters to support the lug area,the wheel is not supported and will crack eventually.
 
When we installed the MT Car Products brake package on the phaeton 10 or 12 years ago it came with the adapter plates. We have used them and driven the car thousands of miles through the Continental divide and back with out cracking a wheel!
 
4banger said:
.... My question is does the outer rim of the spoked wheel hub need to make contact with the brake drum as it does with the original Model A steel brake drums? ....
Click to expand...

I wish it did make contact, but it doesn't. I used the 21" wheels on 40's drums for several years without adapter rings and then for several more years with adapter rings. No problems that I've noticed.

Steve
 
Thank you all for the replies. I have decided to machine the brake drum surface at the rim contact point about 1 1/4 " wide and to machine some spacers to secure to the drums. The spacer attaching screws will be inside the wheel hub rim so as not to be seen when the wheels are attached The spacers will be approx 1/4 thick.
I find in measuring some original steel rims that the measurement from the rim bolting surface to the comtact point of the hub rim is 1.335. All the wheels I measure are 1.350 giving a interferance fit of about .015 This will duplicate the original steel drum to spoke wheel fit.
 
You must log in or register to reply here.
Back
Top